Mucosa is moist tissue that lines some organs and body cavities such as the nose, mouth, lungs and digestive tract. Glands along the mucosa produce a thick fluid called mucus. In the digestive system, mucus acts as a lubricant helping food pass smoothly along the digestive tract. In the stomach and intestinal tract, mucus prevents the highly acidic environment from eating the internal lining of the organs. Interested in learning more about mucosa? Check out the following videos on mucosa. For additional information, also see our mucosa reference materials.